Watching online porn is a good way to get yourself blackmailed by a hacker

Watch online porn? Of course you do. Nothing wrong with that. You’re only human. But we have to warn you: Perusing the NSFW side of the Web could land you with a nasty computer virus that allows criminal hacker gangs to take control of you PC, and hold it hostage until you cough up cash.

Known as “ransomware,” this type of nefarious software is one of the most rapidly spreading threats on the Internet, according to a new report from cybersecurity company Semantic (PDF). The reason: It is an easy way from cybercriminals to make money.

“This malware is highly profitable, with as many as 2.9 percent of compromised users paying out,” the report says. “An investigation into one of the smaller players in this scam identified 68,000 compromised computers in just one month, which could have resulted in victims being defrauded of up to $400,000 USD.”

Semantic researchers Gavin O’Gorman and Geoff McDonald, who authored the ransomware report, say that hacker gangs are likely raking more than $5 million a year by extorting their victims. “The real number is, however, likely much higher,” wrote the researchers.

While about 16 different versions of ransomware viruses exist, says Semantic, they all work in relatively the same way. Hackers trick users into installing the virus on their computer by either installing malicious code on websites, or simply buying ad space on (usually porn) sites, and then running ads that link to a page infected with the ransomware. Once a user clicks the ad, it is secretly installed on their machine through the browser.

After the virus has successfully installed, things immediately go wrong. The ransomware automatically disables a number of key programs that render the computer inoperable by the user. An image will pop up on the screen that is made to look like it’s from a law enforcement agency, like the FBI. The image will tell the user that their computer has been blocked, and they must pay around $200 within 72 hours, or risk arrest for failing to pay a fine for “viewing or distributing prohibited pornographic content”

“Because the compromised individual may have indeed been browsing a pornographic website prior to infection, the message carries some more weight,” the report says. “In addition, the nature of the message may be embarrassing to some, encouraging them to get rid of it at any cost.”

Users tricked by the scheme will then purchase an electronic payment PIN, and enter the number into a box on their computer screen. The hackers can then retrieve the payment. Not surprisingly, however, the hackers rarely uphold their end of the bargain, and victim’s computers remain locked.

According to Semantic, the number of ransomware infections in the U.S. has skyrocketed over the past few months, jumping from about 1-2 percent of total worldwide infections in March to 20-50 percent of infections, as of September.

Fortunately, there are a number of easy ways to avoid infection. First, don’t click any ads on porn sites. Second, make sure all your programs and plugins (like Flash and Java) are all up to date. And finally, install anti-virus software (this is a good free one), which will easily detect any ransomware and clean it off your machine.